Method for determining p1/p2 blood type and detection kit thereof

ABSTRACT

The present invention provides a method for determining P 1 /P 2  blood type, including steps of providing a biological sample of a subject, detecting a genotype for single nucleotide polymorphism rs2143918 or rs5751348 in A4GALT gene of the biological sample and determining a phenotype of the subject based on the genotype. Further, the present invention also provides a kit for determining P 1 /P 2  blood type, including a primer pair for detecting a genotype for single nucleotide polymorphisms rs2143918 or rs5751348 in A4GALT gene of a nucleic acid sample of a subject.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a method for determining P₁/P₂ blood type and a detection kit thereof, and more particularly to a method with a single nucleotide polymorphism for determining P₁/P₂ blood type and a detection kit thereof.

2. Description of Related Art

In 1927, Austrian Biologist Karl Landsteiner and American immunologist Philip Levine discovered a new antigen from the rabbits transfused human blood during research on hemolytic disease of the newborns. These antigens can cause clotting of the red blood cells in some people while other groups of people are unaffected. They namely these two blood types as P₁ (+) and P₁ (−), later, the P1 (+)- and P1 (−) type are referred to as P1 and P2 type. This P₁/P₂ blood type belongs to the third system among the present 33 human blood type.

P₁/P₂ blood type is a system composed of glycolipid antigens; however the molecular genetic basis is still not clear. P₁ blood type and P₂ blood type are correlated to P₁ and P^(k) blood antigens expressed on the red blood cell. The P₁ and P^(k) are carbohydrate antigens and are synthesized via different biosynthetic routes, starting from a common glycosphingolipid precursor, lactosylceramide. The P₁ and P^(k) antigens are determined by the enzymatic activity of α-1,4-galactosyltransferase (hereinafter referred to as A4GALT). P₁/P₂ blood type is a common phenotypic polymorphism and the distribution of which varies among different human populations. The frequency of P₁ type in Caucasians and Africans are 80% and 90-95%, respectively, while the frequency of P₁ type is relatively low in Asians. The frequency of P₁ blood type is about 30% to 40% in Taiwan.

Using DNA genotype as a method for detecting blood type will be a trend in the future. For instance, Progenika Biopharma, S.A. (Spain) has developed a blood chip and such blood chip contains various genotype variations of different blood type. However, in the past, the molecular genetic mechanism of P₁/P₂ blood type has not been verified, such that the current DNA test including Progenika blood chip could not contain this common P₁/P₂ blood type polymorphism to perform DNA analysis. Therefore, there still is a need for determining the P₁/P₂ blood type.

Thuresson et al. (Thuresson B, Westman J S, Olsson M L, Identification of a novel A4GALT exon reveals the genetic basis of the P₁/P₂ histo-blood groups. Blood. 2011; 117(2): 678-687.) has reported the association between SNP rs8138197 and P₁/P₂ phenotypes, and proposed a novel molecular model of the formation of P₁/P₂ blood group.

The present invention utilizes a genetic association study among different ethnic populations to prove single nucleotide polymorphism (hereinafter referred to as SNP) rs2143918 and rs5751348 in A4GALT gene are completely associated with P₁/P₂ blood type. The result of the present invention provides the molecular genetic mechanism of P₁/P₂ blood type and further provides a marker for determining P₁/P₂ blood type by using the genotypes of SNPs rs2143918 and rs5751348.

SUMMARY OF THE INVENTION

The present invention aims to conduct a pilot investigation among four ethnic groups, and the results from analysis of P₁ type of Africans and a Taiwanese family pedigree labeled M3 reveals that a genotype of SNP rs8138197 is not associated with P₁/P₂ blood type.

The present invention provides a method for determining P₁/P₂ blood type, comprising steps of: providing a biological sample of a subject; detecting a genotype for a single nucleotide polymorphism at rs2143918 or rs5751348 in A4GALT gene of the biological sample; and determining a phenotype of the subject based on the genotype.

In one embodiment of the present invention, the genotype of the single nucleotide polymorphism at rs2143918 is selected from the group consisting of T/T, T/G and GIG In one embodiment of the present invention, T/T or T/G genotype of the single nucleotide polymorphism at rs2143918 represents P₁ phenotype in the subject.

In one embodiment of the present invention, G/G genotype of the single nucleotide polymorphism at rs2143918 represents P₂ phenotype in the subject.

In one embodiment of the present invention, the genotype of the single nucleotide polymorphism at rs5751348 is selected from the group consisting of G/G, G/T and TIT.

In one embodiment of the present invention, G/G or G/T genotype of the single nucleotide polymorphism at rs5751348 represents P₁ phenotype in the subject.

In one embodiment of the present invention, T/T genotype of the single nucleotide polymorphism at rs5751348 represents P₂ phenotype in the subject.

In one embodiment of the present invention, the biological samples are blood or saliva.

In one embodiment of the present invention, a nucleic acid in the biological sample is determined by polymerase chain reaction (hereinafter referred to as PCR).

In one embodiment of the present invention, a primer pair of SEQ ID Nos: 1 and 2 are used in the PCR for determining the nucleic acids of the biological samples.

In one embodiment of the present invention, a primer pair of SEQ ID Nos: 3 and 4 are used in the PCR for determining the nucleic acids of the biological samples.

The present invention also provides a detection kit for determining P₁/P₂ blood type, comprising: a primer pair for determining a genotype of a single nucleotide polymorphism at rs2143918 or rs5751348 of A4GALT gene in a nucleic acid sample of a subject.

In one embodiment of the present invention, the primer pair has sequences of SEQ ID Nos: 1 and 2.

In one embodiment of the present invention, the primer pair has sequences of SEQ ID Nos: 3 and 4.

In one embodiment of the present invention, the genotype of the single nucleotide polymorphism at rs2143918 is selected from the group consisting of T/T, T/G and GIG

In one embodiment of the present invention, T/T or T/G genotype of the single nucleotide polymorphism at rs2143918 represents P₁ phenotype in the subject.

In one embodiment of the present invention, G/G genotype of the single nucleotide polymorphism at rs2143918 represents P₂ phenotype in the subject.

In one embodiment of the present invention, the genotype of the single nucleotide polymorphism at rs5751348 is selected from the group consisting of G/G, G/T and T/T.

In one embodiment of the present invention, G/G or G/T genotype of the single nucleotide polymorphism at rs5751348 represents P₁ phenotype in the subject.

In one embodiment of the present invention, T/T genotype of the single nucleotide polymorphism at rs5751348 represents P₂ phenotype in the subject.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows distributions of the most likely haplotype pairs in P₁/P₂ individuals across 4 ethnic populations; and

FIG. 2 shows P₁/P₂ phenotypes and the most likely haplotype pairs of M3 family.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following specific examples are used for illustrating the present invention. A person skilled in the art can easily conceive the other advantages and effects of the present invention. The present invention can also be implemented by different specific cases be enacted or application, the details of the instructions can also be based on different perspectives and applications in various modifications and changes do not depart from the spirit of the creation.

The present invention provides a method for determining P₁/P₂ blood type, comprising steps of providing a biological sample of a subject; determining a genotype for a single nucleotide polymorphism (SNP) of A4GALT gene from the biological samples, wherein the SNP is located at SNP rs2143918 or SNP rs5751348; and discriminating the subject has P₁ or P₂ phenotype according to the genotype of SNP rs2143918 or SNP rs5751348.

The present invention also provides a kit for determining P₁/P₂ blood type, comprising a PCR primer pair, which is used to amplify nucleic acid fragments of a single nucleotide polymorphism of A4GALT gene by using the nucleic acid of the subject to be determined as a template. The single nucleotide polymorphism is located at SNP rs2143918 or SNP rs5751348, wherein the PCR primer pair can perform an extension reaction of the primer so as to determine the genotype of SNP rs2143918 or SNP rs5751348 and discriminate the subject has P₁ or P₂ phenotype.

Example 1: Method for Determining P₁/P₂ Phenotype

1. Sample Preparation and P₁/P₂ Phenotype

A total of 338 non-related subjects across four ethnic populations, including 227 Taiwanese, 32 Indians, 46 Caucasians, and 33 Africans (Blacks, including 2 African-Americans) were enrolled in the present invention. Peripheral blood samples were collected from each subject. The genomic DNAs were purified from the peripheral blood samples using QIAamp DNA Blood Mini Kit (Qiagen GmbH, Hilden, Germany), and then the P₁/P₂ phenotype of each sample was determined by a standard hemagglutination test using monoclonal anti-P1 reagent (Immucor Inc., Houston, Tex.).

2. Analysis of the Single Nucleotide Polymorphism

57 DNA fragments were amplified by polymerase chain reaction (hereinafter referred to as PCR), and these encompassed all SNP sites distribute from −7.0 kb to +17.3 kb of the A4GALT gene. The sequences of PCR primer pairs locations thereof are listed in Table 1. Then, the nucleotides at the SNP sites were determined by direct sequencing the amplified DNA fragments using Sanger's method.

TABLE 1 PCR primers for SNP analysis primer sequence(5′→3′) location^(a) 930R GTGCATGCCTGTAATCACAG  −7085 930F GTGTCACAGTGACTGCTGTG  −6765 217F ATTGACAAGGGCGAGCCAC  −6800 217R AAGCAAACACTCCTCCCTCC  −6618 928R ATGGGTGGAGTGGAAAGTG  −6564 928F AAGACAGAGTCTCCCTGTC  −6236 931F TGTGGCTCTGACTACTGAG   −713 931R ACACACCTAGAAGCCATCC  −5983 678F GCAGTGGCTCCCTTGACATAAGTAACTCC  −5265 677R TTATGTCAAGGGAGCCACTG  −5285 677F GTCAACATCTAGACCACTGC  −4950 584F ACCAGAAAGTTGGAGCTAGG  −5129 584R AACTGGAGCTGGTCATCTGG  −4521 331R ATCTGCTTTGGAGCATGGGC  −4834 331F CTGGGATTACAGGCGTGAGC  −4437 853R CAGCTCCAGTTTACTGATGG  −4532 853F GTCAGGCTGGTCTTGATCAC  −4056 690F1 CAAGACCAGCCTGACCAACG  −4070 690R2 GGTTGAGCACACAGGCTCTG  −3480 628R2 CTCTCAGAGCCTGTGTGCTC  −3503 628F1 AGCCCCAGCAGCCTTTGAG  −3193 644F AATGATCCTACTGCCTCAGC  −3078 676F TATTCAAGGCAGGCCAGCAC  −2182 676R TCGCTCTGTCGCCATACTGG  −2684 676F TATTCAAGGCAGGCCAGCAC  −2182 795F CTCAGCCTCCCACAGTGTGG  −1607 795R GACGGAGTCTCACTCTGTCG  −2138 326R GTTGCCTTCTAGTCTCTGAG  −1783 326F GAAGAGACTCACTCTGTTACC  −1383 035R TTAGCCATGGTTGTGCATGCCTGTAGTCC  −1524 035F AGGCCAGGCAAGCACTCACGCCTGTAATC  −1056 369R ATCTCAGGTGACCTGCTTGC  −1125 369F GGGTGACTTCTTGAGTGCTG   −680 898R ACCCATTGAGTGCCAGGCTC   −799 898F ACCGTGCTAAGGGCATTGCC   −373 A4GTFa CACCAGGACTGTGACATGCTGGAAACATGG   −626 PKRL CTGCCTCGAACCCGGCTTCT   +430 469F3 GGAGAAGCCGGGTTCGAGGCAGGCTCTGC   +409 469R4 GCTTTAACCCACTCAGGGCCAGAGGCTCAGC   +939 845R GTGAGGATTTGGACCTGCCC   +596 927F ACTACAGTGAGCTGCCACAG  +1472 573R CAACGTCGAGTGATTGTTCC  +1002 573F GGTTGCAGCTATGGAAACAC  +1303 927R ATAGCAGAGTGCGGATGGAG  +1188 927F ACTACAGTGAGCTGCCACAG  +1472 672R TGTAGTCTCAAACTGCTAGG  +1467 672F CAATCCTGCTCCACACTGG  +1783 920R GCTGCTAGGTTAATGGGTCC  +1710 920F TTCAGGAAGCACCTGCTAGG  +2186 522R AAGTGCACCTCCTCTCACTC  +1985 522F CTCACTGCACTCTCTGCCTC  +2538 175F TCTAGCTTTCCCATCAGC  +3239 926R GACAGAGAGATAGAGAGGAG  +3132 926F TATGTGGACACTGGTCTGG  +3800 991R CCTTCCAGACCAGTGTCCAC  +3778 991F AACAGAGCATGGTGGCTGAG  +4136 181R CCCTGATCATCTGTGACC  +4018 181F AAAAGCTCACTGTCAGGC  +4501 181Fs CTATTAAACCACACAGCTCC  +4462 860F ATTAGCAGGGAATGGTGG  +5307 183F GAGTGCACTGGTGCAATCATG  +5189 183R CTTCATACCATAAATTCCAAG  +5674 894R GTCCTTCAGCAGCTCTCAAG  +5750 892R TGGCTCCCTCCTGTAATTC  +6553 176F GGAGTGCGGTGGTATGAG  +6627 858R ATCTGGCAAAACCCCACCTC  +7245 245F CCTAACCTCAGGTGATCCACC  +7267 245R CTCCCCCAGCATCACCTAC  +7915 718F CCCCTTCTCAGGCAGTATCC  +7843 718R CACCTTCGCTCTGGACAC  +8550 291F TTGCATCTCTGGGATCTCTG  +8429 291R AGTACCTGACTACTTGCCAG  +8760 888F TGAGAAGCCAGCCCCACC  +8637 888R CCGAGTCTCGCTCTGTTGCC  +9215 185F GAGGTTGTAGTGAGCCAAG  +9153 185R CTGTGAGCAAACAGGCATG  +9533 306F TGTGGTAGGATCTGTGCTGG  +9272 306R TAGCTACTCAGGAGGCTGAG  +9942 887R TGCAGCAAGCCAAGATGGTG +10216 887F AGCCTCCTGAGTAGCTAGGG  +9926 081F CATCTTGGCTTGCTGCAGCC +10200 081R ACAGTTTCATACCTGGGCAC +10779 347R GCTCAAGCAATCTGGCTGCC +10368 347F ACACAGAAGCCAGGAACCAG +10825 793F TGGTGGTGGCAGCATCTGTG +10719 793R GGCAGGTGGATCACTTGAGG +11293 653F GATTACAGTTGTGCCCCACC +11179 479R CAAGTACATGATCCTCCCAC +11697 616F TGGGAGCCTAGGAATTCAAG +11563 616R GGATCCCAGAAGACATAGC +11988 993F GTAGATTAGCTATGTCTTCTGGG +11962 993R ATCGCGCCATTGCATTCTAG +12521 227F CTGGCACTGCAGGTACACAC +12422 227R ACACAGAAACATGGCTGGTC +13012 634F ATTGTTACATACACTGGTGG +13082 634R ACTCTCTACCCTAGTGATAG +13708 280F GCACAGTATCTATCACTAGG +13680 280R GAGACATACCTTAAACGAAG +14387 712R ATCCTGGCTAACACGGTG +14693 036F TCAGCCTCCCGAGTAACTG +14594 036R TCGCTTGAACCTGGGAAGTG +14884 903F CCTCGGCCTATTAAAGTGC +15079 903R TGAGGAGCACAAATACTCGC +15590 557F AGCGAGTATTTGTGCTCCTC +15570 557R AAGACCCCAGAAAAGGCC +15934 881F AAAGGCTCCCTCCTCTGTTG +15731 881R GAAGCCAGGAATCAAGCAGG +16230 436F TCTGTTTGTAACGTCCACCC +16177 436R CCTTCACTGCTTTGTCCATC +16889 193F GCAGGGTTTGGAAGCTCTGG +16787 193R TGTGCCCGGCCTGCAATAAG +17308 ^(a)Transcription initiation nucleotide of A4GALT exon 1 of RefSeq Transcript

3. Primer Pairs for Amplification and Identification of the Genotypes of Rs2143918 and rs5751348

The forward primer for amplification and identification the genotype of rs2143918 has the sequence of SEQ ID No. 1, while the reverse primer has the sequence of SEQ ID No. 2.

AAGTGCACCTCCTCTCACTC (SEQ ID NO. 1) TCTAGCTTTCCCATCAGC (SEQ ID NO. 2)

The forward primer for amplification and identification the genotype of rs5751347 has the sequence of SEQ ID No. 3, while the reverse primer has the sequence of SEQ ID No. 4.

TCACGAGCATTCCTCATC (SEQ ID NO: 3) CTCCTCTCTATCTCTCTGTC (SEQ ID NO: 4)

4. Result

1) A pilot investigation for identification of SNPs in A4GALT gene associated with the P₁/P₂ phenotype.

In order to explore the molecular genetic basis of the P₁/P₂ blood groups, the present invention conducted a pilot investigation, which involved the detailed and stepwise screening of SNPs in A4GALT gene from four Taiwanese with the P₁ phenotype and four Taiwanese with the P₂ phenotype. The screening of SNP started from the 5′ promoter region and then extended stepwise to the 5′ and 3′ region of the gene to identify any polymorphic nucleotide positions that may be related to P₁/P₂ phenotypes. The PCR, which was used to amplify the DNA fragments encompassing each SNP in the A4GALT gene, has been recorded in the SNP database of the National Center for Biotechnology Information (NCBI). Eventually, 57 DNA fragments were amplified respectively by PCR. The amplified DNA fragments contain a total of 416 different SNP sites which were distributed over 24.3 kb region of the A4GALT gene including 7.0 kb of the 5′ promoter region, exon 1 (74 bp), and 17.3 kb of the 5′ part of intron 1. The nucleotides at each SNP over the eight samples were determined and the results are shown in Table 2. These show that 11 SNP sits of 8 subjects exhibited an association with the P₁/P₂ phenotype. These 11 SNPs are distributed from the +1.3 kb to +11.5 kb region in the intron 1 of the A4GALT gene, and they are denoted as SNP1 to SNP11 from 5′ to 3′.

TABLE 2 SNPs in the A4GALT gene that show an association with the P₁/P₂ blood group phenotypes in the pilot investigation SNP1 SNP2 SNP3 SNP4 SNP5 SNP6 Location^(a) +1352 +2326 +2414 +2837 +2857 +3084 SNP ID rs67162484^(a) rs8138197 rs10713068 rs2143919 rs2143918 rs5751348 rs66781836^(b) Nucleotide AGAA/− C/T C/− C/G T/G G/T Polymorphisms^(c) Phenotype Sample Genotype^(c) P₁ M8 +/+ C/C C/C C/C T/T G/G M5 +/+ C/C C/C C/C T/T G/G M33 +/− C/T C/− C/G T/G G/T HSC +/− C/T C/− C/G T/G G/T P₂ M12 −/− T/T −/− G/G G/G T/T T9 −/− T/T −/− G/G G/G T/T J1 −/− T/T −/− G/G G/G T/T Y1 −/− T/T −/− G/G G/G T/T SNP7 SNP8 SNP9 SNP10 SNP11 Location^(a) +3443 +5012 +6762 +7038 +11507 SNP ID rs9623671 rs111626860 rs5758891 rs8139674 rs66463955 Nucleotide G/A ACTCCA/− T/C G/T G/− Polymorphisms^(c) Phenotype Sample Genotype^(c) P₁ M8 G/G +/+ T/T G/G G/G M5 G/G +/+ T/T G/G G/G M33 G/A +/− T/C G/T G/− HSC G/A +/− T/C G/T G/− P₂ M12 A/A −/− C/C T/T −/− T9 A/A −/− C/C T/T −/− J1 A/A −/− C/C T/T −/− Y1 A/A −/− C/C T/T −/− ^(a)Transcription initiation nucleotide of A4GALT exon 1 (74 bp) of RefSeq Transcript NM_017436.4 in the NCBI database as +1 ^(b)SNPs rs67162484 and rs66781836 yield identical sequence polymorphisms. ^(c)“+” and “−” indicate the presence and the absence of the nucleotide(s), respectively.

2) SNPs Rs2143918 and Rs5751348 Show a Definite Association with the P₁/P₂ Phenotypes Across Different Ethnic Populations.

In order to verify the association of these 11 SNPs (SNP1 to SNP11) and the phenotypes of P₁/P₂ phenotypes, a large scale association study using various ethnic populations was carried out There were 227 Taiwanese (including 8 subjects analyzed in the previous pilot study), 32 Indians, 46 Caucasians and 33 Africans (Black) enrolled in this study. The P₁/P₂ phenotypes and the genotypes at SNP1 to SNP11 of these 338 subjects were determined. The distributions of the genotypes at the 11 SNPs in the P₁ and P₂ individuals of each population are shown in Table 3. The haplotypes of the 11 SNPs in the 4 populations were reconstructed and the most likely haplotype was assigned for each subject using PHASE program (version 2.1). FIG. 1 shows the distribution of the most likely haplotype pairs in the P₁ and P₂ subjects among each ethnic population.

The two haplotypes identified by using 8 Taiwanese in the pilot study were found to be major haplotypes present in the wider study and were also associated with the P₁ and P₂ phenotypes across all four populations. In addition to the two haplotypes found in the four populations, haplotypes with recombination between the 11 SNPs were identified and were found to be more frequent in Caucasians and Africans than in Taiwanese and Indians. The correlation of SNP1, SNP3, SNP4, and SNP7 to SNP11 could be easily excluded while multiple cases distributed across the different ethnic populations were identified as recombinant haplotypes between these SNPs, as shown in Table 3 and FIG. 1. Thus, it creates inconsistencies in the genotype-phenotype correlation observed across the majority of other enrolled subjects.

Among the 338 enrolled subjects, only one subject (P₁ Africans, denoted as ** in Table 3 and * in FIG. 1) showed the genotype-phenotype inconsistency of SNP rs8138197. In the previous analysis for the P₁ and P₂ phenotype from 208 Swedish subjects, there was one case found the genotype-phenotype inconsistency of SNP rs8138197. In addition to such P₁ African case, a P₁ Taiwanese (denoted as * in FIG. 1) labeled as M3 family was pointed out as having an allele which is involved recombination between SNP3 and SNP4. As shown in FIG. 2, the M3 family was then enrolled to perform the pedigree analysis and the recombinant allele identified in M3 was found to be present in M3's father and brother who were labeled with the P₂ phenotype. The results obtained from this pedigree analysis suggest that SNP2 (i.e. rs8138197) is nor involved in defining the P₁ and P₂ phenotypes.

When the above results were taken together, the SNPs that show definite association with the P₁/P₂ phenotypes could be narrowed down to two, namely SNP5 (rs2143918) and SNP6 (rs5751348), using this pilot study across different ethnic populations. The genotypes at the SNPs distributed along the +1.3 kb through +3.7 kb region of the A4GALT gene, which encompasses the SNP1 to SNP7 sites, of the enrolled 338 subjects were thoroughly examined, and no other SNP was found an association with the P₁ and P₂ phenotypes. The genotypes at SNPs rs2143918 and rs5751348 were consistently associated with the P₁ and P₂ phenotypic polymorphisms while 338 subjects across the four ethnic populations have considerable genetic distances.

TABLE 3 SNPs associated with the P₁/P₂ blood group phenotypes and distributions of the SNP genotypes in the P₁ and P₂ subjects of various ethnic populations SNP1 SNP2 SNP3 SNP4 SNP5 SNP6 Location^(a) +1352 +2326 +2414 +2837 +2857 +3084 SNP ID rs67162484^(b) rs8138197 rs10713068 rs2143919 rs2143918 rs5751348 rs66781836^(b) Nucleotide AGAA (▪)/ C (▪)/T C (▪)/—(□) C (▪)/G T (▪)/G G (▪)/T Polymorphisms^(c) —(□) (□) (□) (□) (□) Genotypes^(c) ▪/▪ ▪/□ □/□ ▪/▪ ▪/□ □/□ ▪/▪ ▪/□ □/□ ▪/▪ ▪/□ □/□ ▪/▪ ▪/□ □/□ ▪/▪ ▪/□ □/□ Taiwanese P₁ 5 58 0 5 58  0 5 58 0 4 59 0 4 59 0 4 59 0 (n = 63) P₂ 0 0 164 0 0 164  0 0 164 0 0 164 0 0 164 0 0 164 (n = 164) Indian P₁ 4 16 0 4 16  0 4 15 1 4 15 1 4 16 0 4 16 0 (n = 20) P₂ 0 0 12 0 0 12 0 0 12 0 0 12 0 0 12 0 0 12 (n = 12) Caucasian P₁ 11 21 0 12 20  0 9 17 6 9 17 6 12 20 0 12 20 0 (n = 32) P₂ 0 0 14 0 0 14 0 0 14 0 0 14 0 0 14 0 0 14 (n = 14) African^(d) P₁ 11 17 3 13 17  1* 5 16 10 10 20 1 13 18 0 13 18 0 (n = 31) P₂ 0 0 2 0 0  2 0 0 2 0 0 2 0 0 2 0 0 2 (n = 2) Swedish^(e) P₁ 57 93  1 (n = 151) P₂ 0 0 57 (n = 57) SNP7 SNP8 SNP9 SNP10 SNP11 Location^(a) +3443 +5012 +6762 +7038 +11507 SNP ID rs9623671 rs111626860 rs5758891 rs8139674 rs66463955 Nucleotide G (▪)/A ACTCCA T (▪)/C G (▪)/T G (▪)/—(□) Polymorphisms^(c) (□) (▪)/—(□) (□) (□) Genotypes^(c) ▪/▪ ▪/□ □/□ ▪/▪ ▪/□ □/□ ▪/▪ ▪/□ □/□ ▪/▪ ▪/□ □/□ ▪/▪ ▪/□ □/□ Taiwanese P₁ 4 59 0 4 59 0 4 59 0 4 59 0 4 59 0 (n = 63) P₂ 0 0 164 0 0 164 0 1 163 0 5 159 0 2 162 (n = 164) Indian P₁ 4 15 1 4 15 1 4 15 1 6 13 1 4 15 1 (n = 20) P₂ 0 0 12 0 0 12 0 0 12 0 0 12 0 0 12 (n = 12) Caucasian P₁ 9 17 6 9 17 6 8 18 6 8 20 6 8 18 6 (n = 32) P₂ 0 0 14 0 0 14 0 0 14 0 2 10 0 1 13 (n = 14) African^(d) P₁ 10 20 1 9 21 1 11 20 0 18 13 0 12 19 0 (n = 31) P₂ 0 0 2 0 0 2 0 0 2 0 0 2 0 0 2 (n = 2) Swedish^(e) P₁ (n = 151) P₂ (n = 57) The numbers of the individuals that show genotype-phenotype inconsistency compared to the majority of others are typed in red. ^(a)Transcription initiation nucleotide of A4GALT exon 1 (74 bp) of RefSeq Transcript NM_017436.4 in the NCBI database as +1 ^(b)SNPs rs67162484 and rs66781836 yield identical sequence polymorphisms. ^(c)The two different nucleotide genotypes at each SNP are denoted by ▪ and □. ^(d)An asterisk indicates a P₁ African who shows a genotype-phenotype discrepancy at SNP2. ^(e)Ref. 28. The association dataset for the other SNPs in this population is not available.

By a pilot investigation and stepwise SNP screening analysis in A4GALT gene followed by an association study using four ethnic populations, the present invention confirms that SNPs rs2143918 and rs5751348 are correlated with the P1 and P2 blood type. Accordingly, the T/T and T/G genotypes at the SNP rs2143918 are associated with P₁ phenotype while the G/G genotype at the SNP rs2143918 is associated with P₂ phenotype. The G/G and G/T genotypes at the SNP rs5751348 are associated with P₁ phenotype while the T/T genotype at the SNP rs5751348 is associated with P₂ phenotype.

While some of the embodiments of the present invention have been described in detail in the above, it is, however, possible for those of ordinary skill in the art to make various modifications and changes to the particular embodiments shown without substantially departing from the teaching and advantages of the present invention. Such modifications and changes are encompassed in the spirit and scope of the present invention as set forth in the appended claim. 

1. A method for detecting P₁/P₂ blood type, comprising: obtaining a biological sample from a subject; purifying genomic DNA from the biological sample of the subject; amplifying a DNA fragment of α-1,4-galactosyltransferase (A4GALT) gene from the genomic DNA using a kit comprising a reaction mixture, a first primer and a second primer; and detecting a single nucleotide polymorphism at rs5751348 of the A4GALT gene from the amplified DNA fragment. 2-4. (canceled)
 5. The method of claim 1, wherein the genotype of the single nucleotide polymorphism at rs5751348 is G/G, G/T or T/T.
 6. The method of claim 5, wherein the genotype of the single nucleotide polymorphism at rs5751348 as G/G or G/T indicates the subject having P₁ blood phenotype.
 7. The method of claim 5, wherein the genotype of the single nucleotide polymorphism at rs5751348 as T/T indicates the subject having P₂ blood phenotype.
 8. The method of claim 1, wherein the biological sample is blood or saliva.
 9. (canceled)
 10. The method of claim 1, wherein the first primer is SEQ ID No:
 3. 11. The method of claim 1, wherein the second primer pair is SEQ ID NO:
 4. 12-20. (canceled) 